diff --git a/app/models/topic_link.rb b/app/models/topic_link.rb
index 37d7b656dde..d7691db82d2 100644
--- a/app/models/topic_link.rb
+++ b/app/models/topic_link.rb
@@ -57,7 +57,8 @@ SQL
 
     builder.where('ftl.topic_id = :topic_id', topic_id: topic_id)
     builder.where('ft.deleted_at IS NULL')
-    builder.where("NOT(ftl.url LIKE '%.png' OR ftl.url LIKE '%.jpg' OR ftl.url LIKE '%.gif')")
+    # note that ILIKE means "case insensitive LIKE"
+    builder.where("NOT(ftl.url ILIKE '%.png' OR ftl.url ILIKE '%.jpg' OR ftl.url ILIKE '%.gif')")
     builder.where("COALESCE(ft.archetype, 'regular') <> :archetype", archetype: Archetype.private_message)
 
     builder.secure_category(guardian.secure_category_ids)